TW201835630A - Optical lens - Google Patents

Abstract

An optical lens including a first lens group, an aperture stop, and a second lens group arranged in order from a magnified side to a minified side is provided. The first lens group has an outmost lens facing the magnified side, and the second lens group has an outmost lens facing the minified side. At least one of the outmost lens of the first lens group and the outmost lens of the second lens group is formed of glass. At least one of the first lens group and the second lens group has a lens having negative refractive power and being composed of plurality of lenses being mutually contacted to each other. The condition: TTL < 100 mm is satisfied, wherein TTL denotes a length measured along an optical axis and between two outmost opposite lens surfaces of the optical lens.

Description

Optical lens

The present invention relates to an optical lens, and more particularly to a telecentric lens.

In general, if the projector is to be projected onto a larger screen, it must have a longer projection distance. In contrast, to project a large size picture at a shorter projection distance, a special wide-angle lens must be used to shorten the distance from the projection screen to the projector. Therefore, the wide-angle lens can effectively shorten the distance between the projection screen and the projector and obtain a large-sized projection screen. However, the aberrations derived from wide-angle projection lenses are a problem that designers must face. Furthermore, in order to cope with the increase in imaging circles, optical lenses must be designed to meet the optical requirements of different projection sizes to achieve good optical quality.

The present invention provides an optical lens which has low cost and good optical characteristics.

In an embodiment of the invention, the optical lens (for example, a telecentric lens) includes a first lens group, an aperture stop, and a second lens group in order from the magnification side to the reduction side. Each of the first lens group and the second lens group has a lens having the diopter and the aspherical surface from the outermost side of the aperture stop. The outermost lenses of the first lens group and the second lens group face the reduction side and the magnification side, respectively, and the outermost lens of the second lens group is formed of glass. In addition, the second lens group further includes a triplet lens combined by three lenses having a negative total refracting power. Furthermore, the total length of the optical lens between the two outermost lenses along the optical axis is less than 100 mm.

Based on the above, the optical lens provided in the embodiment of the present invention provides a solution to low temperature influence and deformation.

The above described features and advantages of the invention will be apparent from the following description.

The foregoing and other technical features, features and advantages of the present invention will be apparent from the Detailed Description of the <RTIgt;

The terms "first" and "second" used in the following examples are used to identify the same or similar elements, and are not intended to limit the elements.

The so-called optical element of the present invention is composed of a material having a part or all of which can be reflected or penetrated, and generally comprises glass or plastic.

The term "lens" as used in the present invention refers to an optical element which at least allows a part of light to penetrate and whose radius of curvature of at least one of the light-in and light-emitting surfaces is not infinite; in other words, at least the entrance and exit surfaces of the lens One of them needs to be non-planar. For example, flat glass is not the lens referred to in the present invention.

The so-called magnification side of the present invention refers to the side closer to the projection surface (for example, the projection screen) when the lens is applied to the projection system, and the side closer to the light valve when the lens is closer to the projection surface. When the lens is applied to the image taking system, the magnification side refers to the side close to the object, and the reduction side refers to the side closer to the photosensitive element.

The so-called lens group of the present invention includes one or more lenses.

1A is a schematic view of an optical lens in accordance with an embodiment of the present invention. Referring to FIG. 1A, the optical lens 100 provided in this embodiment may be a telecentric lens system and has an optical axis A, and the optical lens 100 is located between the magnification side OS and the reduction side IS. The optical lens 100 includes a first lens group 110, an aperture stop S, and a second lens group 120. It should be noted that the lens group may include only one lens unless otherwise stated, but the present invention is not limited thereto. The first lens group 110 is disposed between the magnification side OS and the aperture stop S, and the first lens group 110 has a positive refracting power. The second lens group 120 is located between the aperture stop S and the reduction side IS, and the second lens group 120 has a positive refracting power. The optical lens 100 is capable of forming an image on the magnification side OS.

In the present embodiment, the first lens group 110 includes a first lens G1, a second lens G2, and a third lens G3 which are sequentially arranged from the magnification side OS to the reduction side IS. The second lens group 120 includes a fourth lens G4, a fifth lens G5, a sixth lens G6, and a seventh lens G7 which are sequentially arranged from the magnification side OS to the reduction side IS.

The first lens G1 and the seventh lens G7 are the outermost lenses of the first lens group 110 and the second lens group 120, respectively. Specifically, the first lens G1 is a lens having a diopter that is the furthest from the aperture side S along the optical axis A toward the magnification side OS, or is enlarged in the first lens group 110, in the first lens group 110. The nearest diopter lens of the side OS. The outermost surface of the first lens G1 faces the magnification side OS. Specifically, the seventh lens G7 is a diopter lens which is the furthest from the aperture stop S along the optical axis A in the second lens group 120, or has a diopter closest to the reduction side IS in the second lens group 120. Lens. The outermost surface of the seventh lens G7 faces the reduction side IS.

In the present embodiment, the second lens group 120 includes four lenses, and at least three of the four lenses are fixed to each other. More specifically, the fourth lens G4, the fifth lens G5, and the sixth lens G6 are sequentially arranged from the magnification side OS to the reduction side IS, and the fourth lens G4, the fifth lens G5, and the sixth lens G6 are in contact with each other and fixed. Together to form a triple cemented lens. The lens can be fixed by gluing or mechanical means.

In the present embodiment, the diopter of the first lens G1 to the seventh lens G7 are negative, negative, positive, negative, positive, negative, and positive, respectively. The second lens G2, the fourth lens G4, the fifth lens G5, the sixth lens G6, and the seventh lens G7 are all formed of glass, and the first lens G1 and the third lens G3 are respectively formed of plastic. On the other hand, the temperature coefficients of refractive index of the second lens G2, the fourth lens G4, the fifth lens G5, the sixth lens G6, and the seventh lens G7 may be optionally positive values, so that Aberration caused by an increase in temperature can give better performance. Also, the refractive index temperature coefficients of the first lens G1 and the third lens G3 may be optionally a negative value.

Further, according to the present embodiment, the image processing element 130 may be disposed on the reduction side IS to input or output image light, and further, a virtual imaging plane is formed on the surface of the image processing element 130. The image processing component 130 described in the embodiment may refer to at least one light valve, and the light valve may be a digital micromirror device (DMD) or a liquid crystal display (LCD), etc., and in the embodiment, the light valve is a DMD. In some related embodiments, optical lens 100 further includes an optical element such as an internal total reflection iridium (TIR prism) or field lens between seventh lens G7 and image processing element 130. Further, the field lens may refer to a lens disposed adjacent to the digital micromirror element and in which both the illumination light and the image light can pass therethrough.

In the present embodiment, the optical lens 100 is a projection lens for a pico projector or a PICO projector, and is, for example, a projection lens having a fixed focal length. In detail. The image light is input from the seventh lens G7 and output from the first lens G1, and then the imaging light is projected toward the magnification side OS. The diagonal length of the light valve is, for example, 0.3 inches, and its resolution is, for example, 1280×720. Further, the positions of the first lens group 110 and the second lens group 120 of the optical lens 100 are relatively fixed, and both the first lens group 110 and the second lens group 120 can be moved together to focus the optical lens 100.

The following will refer to the specific data of each lens in the optical lens 100 illustrated in FIG. 1A. (Table 1)

In Table 1, the symbol using * is represented as an aspherical surface. Spacing refers to the linear distance between two adjacent surfaces on the optical axis A. For example, the distance between the surfaces S1, that is, the linear distance between the surface S1 and the surface S2 on the optical axis A. Table 1 shows the thickness, refractive index, and Abbe number of each lens, and the corresponding columns are described in the remark column. Further, in Table 1, the surfaces S1, S2 are the both surfaces of the first lens G1, and the surface S1 faces the magnification side OS. The surface S7 refers to the aperture stop S, the surface S9 is a glued surface and is connected to the fourth lens G4 and the fifth lens G5, and the surfaces S9 and S10 are all glued surfaces, and the fourth lens G4, the fifth lens G5 and the sixth lens G6 are connected. .

In the present embodiment, the surfaces S1, S2, S3, S4, S5, S6, S12, and S13 are aspherical surfaces, and can be expressed by the following formula (1): (1)

In equation (1), Z is the offset (sag) in the direction of the optical axis A, and c is the reciprocal of the radius of the osculating sphere, that is, the radius of curvature near the optical axis A (as in S1 in Table 1). The reciprocal of the radius of curvature to S6 and S12 to S13; k is the quadric coefficient (conic), r is the aspherical height, that is, the height from the center of the lens toward the edge of the lens, and A ₂ , A ₄ , A ₆ , A ₈ , A ₁₀ , A ₁₂ , A ₁₄ , A ₁₆ ... are aspheric coefficients, and in the present embodiment, the coefficient A ₂ is zero. The parameter values of the surfaces S1 to S6 and the surfaces S12 to S13 in the optical lens 100 are listed in Table 2. (Table 2)

In the optical lens 100 of the present embodiment, the focal length of the first lens group 110 is 24 mm, the focal length of the second lens group 120 is 13 mm, and the effective focal length (EFL) of the optical lens 100 is 7.813 mm, and the aperture value (Fno) is 1.7. The total lens length (TTL) between the surface S1 and the surface S13 is 41.86 mm. The projection ratio (TR) of the optical lens 100 can be between 0.5 and 2, and the projection ratio of this embodiment is about 1.1. Further, for example, in the present embodiment, since the seventh lens G7 close to the light valve is formed of glass, the influence of heat on the optical quality of the optical lens 100 can be reduced.

Further, in the present embodiment, the first lens G1, the second lens G2, the third lens G3, and the seventh lens G7 respectively include at least one aspherical surface. The fourth lens G4, the fifth lens G5, and the sixth lens G6 are formed as a three-glued lens, so that the distortion of the projected image can be reduced, the chromatic aberration can be reduced, and the resolution can be improved.

Further, in the present embodiment, the optical lens 100 satisfies the following conditions (1) to (2). TTL<100 mm (1) 2.5<TTL/EFL<6.5 (2)

Here, TTL denotes a measured length along the optical axis A between the first and last surfaces of the optical lens, and more specifically, this length is the measured length between the outermost surfaces of the two lenses in the optical lens 100. In the present embodiment, TTL represents the measured length along the optical axis A between the surface S1 of the first lens G1 and the surface S13 of the seventh lens G7. Further, the EFL is expressed as an effective focal length of the optical lens 100.

1B to 1E are diagrams of imaging optical simulation data of the optical lens of FIG. 1A. FIG. 1B shows a diffraction modulation transfer function of the optical lens 100. 1C shows the modulation transfer function of the optical lens 100, whose horizontal axis is represented as a spatial frequency per cycle/mm, and the vertical axis is expressed as a modulus of an optical transfer function (OTF). 1D and 1E show simulated patterns of field curvature and distortion using light having a wavelength of 623 nm, light having a wavelength of 525 nm, and light having a wavelength of 460 nm, respectively. In the present embodiment, the distortion rate is, for example, less than 0.5%. In detail, the distortion rate in this embodiment is less than 0.2%.

The reference numerals and some descriptions provided in the foregoing embodiments are also applicable to the following embodiments. The same reference numerals denote the same or similar elements in the present embodiment and the foregoing embodiments, and the repeated description is omitted. The omitted description can be found in the foregoing exemplary embodiment.

2A is a schematic view of an optical lens in accordance with another embodiment of the present invention. Refer to Figure 1. Referring to FIG. 1A and FIG. 2A, the optical lens 200 provided in the present embodiment is similar to the optical lens 100 provided in the embodiment shown in FIG. 1A, and the differences are as follows. The optical lens 200 includes a first lens group 210, an aperture stop S, and a second lens group 220. The image processing elements 230 may be arranged on the reduction side IS. In addition, the third lens G3 in this embodiment is a lenticular lens, and the fourth lens G4 in this embodiment is a double concave lens.

Further, in the present embodiment, the diopter of the first lens G1 to the seventh lens G7 are negative, negative, positive, negative, positive, negative, and positive, respectively. In the present embodiment, the first lens G1, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6, and the seventh lens G7 are all formed of glass, and the second lens G2 is formed of plastic.

The following will refer to the specific data of each lens in the optical lens 200 illustrated in FIG. 2A. (table 3)

The manner in which the data and optical parameters in Table 3 are interpreted is similar to Table 1, and therefore will not be repeated below. In the present embodiment, the surfaces S1, S2, S3, S4, S12, and S13 are aspherical surfaces, and can be expressed by the above formula (1). The parameter values of the surfaces S1 to S4 and the surfaces S12 to S13 in the optical lens 200 are listed in Table 4. (Table 4)

2B to 2E are diagrams of imaging optical simulation data of the optical lens of Fig. 2A. FIG. 2B shows a diffraction modulation transfer function of the optical lens 200. FIG. 2C shows the modulation transfer function of the optical lens 200. 2D and 2E show simulated patterns of field curvature and distortion using light of wavelengths of 623 nm, 525 nm, and 460 nm, respectively. In the present embodiment, the distortion rate is, for example, less than 0.5%.

3A is a schematic view of an optical lens in accordance with another embodiment of the present invention. Referring to FIG. 1A and FIG. 3A, the optical lens 300 provided in this embodiment is similar to the optical lens 100 provided in the embodiment shown in FIG. 1A, and the differences are as follows. The optical lens 300 includes a first lens group 310, an aperture stop S, and a second lens group 320. The image processing elements 330 may be arranged on the reduction side IS. The fourth lens G4 is a convex-concave lens having a concave surface facing the reduction side IS. Further, in the present embodiment, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6, and the seventh lens G7 are formed of glass, and the first lens G1 is a plastic lens. Further, in the present embodiment, the diopter of the first lens G1 to the seventh lens G7 are negative, positive, positive, negative, positive, negative, and positive, respectively.

The following will describe the specific data of each lens in the optical lens 300 illustrated in FIG. 3A. It should be noted, however, that the present invention is not limited to the data listed in Tables 1 to 6. It will be apparent to those skilled in the art that various modifications and changes can be made to the parameters or arrangements provided herein without departing from the scope and spirit of the invention. (table 5)

The manner in which the data and optical parameters in Table 5 are interpreted is similar to Table 1, and therefore will not be repeated below. In the present embodiment, the aspherical surface can be expressed by the above formula (1). The parameter values of the surfaces S1 to S6 and the surfaces S12 to S13 in the optical lens 300 are listed in Table 6. (Table 6)

3B to 3E are diagrams of imaging optical simulation data of the optical lens of FIG. 3A. FIG. 3B shows a diffraction modulation transfer function of the optical lens 300. 3C shows the modulation transfer function of the optical lens 300, the horizontal axis of which represents the spatial frequency per cycle/mm, and the vertical axis represents the modulus of the optical transfer function. 3D and 3E show simulated patterns of field curvature and distortion using light having wavelengths of 623 nm, 525 nm, and 460 nm, respectively. In the present embodiment, the distortion rate is, for example, less than 0.5%. In detail, the distortion rate in this embodiment is less than 0.2%. The patterns provided in the embodiments shown in FIGS. 1B to 1E, 2B to 2E, and 3B to 3E are within the standard range, and thus the optical lens 100 and the optical lens provided in the embodiment of the present invention are provided. Both the 200 and the optical lens 300 can meet the requirements of low cost, miniaturization, thinning, high resolution, low distortion, large aperture diaphragm, good optical quality, and good throw ratio to meet the optical requirements of different projection sizes.

In summary, the optical lens provided in this paper meets the requirements of low cost, miniaturization, thinning, high resolution, low distortion, large aperture diaphragm, good optical quality and good throw ratio to meet the optical requirements of different projection sizes. .

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

100, 200, 300‧‧‧ optical lenses

110, 210, 310‧‧‧ first lens group

120, 220, 320‧‧‧ second lens group

130, 230, 330‧‧‧ image processing components

A‧‧‧ optical axis

G1, G2, G3, G4, G5, G6, G7‧‧ lens

IS‧‧‧ reduction side

OS‧‧‧Amplification side

S‧‧‧ aperture diaphragm

S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13‧‧‧ surface

1A is a schematic view of an optical lens in accordance with an embodiment of the present invention. 1B to 1E are diagrams of imaging optical simulation data of the optical lens of FIG. 1A. 2A is a schematic view of an optical lens in accordance with another embodiment of the present invention. 2B to 2E are diagrams of imaging optical simulation data of the optical lens of Fig. 2A. 3A is a schematic view of an optical lens in accordance with another embodiment of the present invention. 3B to 3E are diagrams of imaging optical simulation data of the optical lens of FIG. 3A.

Claims (10)

An optical lens comprising, in order from the magnification side to the reduction side, a first lens group having at least one lens, an aperture stop, and a second lens group having a plurality of lenses in contact with each other and having a negative refracting power a lens, wherein a lens having a refracting power farthest from the aperture stop in the first lens group has an aspherical surface, and a lens having a refracting power farthest from the aperture stop in the second lens group has an aspherical surface and The glass is formed, and the TTL is the length measured along the optical axis between the opposite surfaces of the two lenses farthest from the optical lens, and the optical lens satisfies the condition of TTL < 100 mm. The optical lens of claim 1, wherein the first lens group comprises a first lens, a second lens and a third lens arranged in sequence from the magnification side toward the reduction side, the second lens group comprising a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged in this order from the magnification side toward the reduction side, wherein the fourth lens, the fifth lens, and the sixth lens are in contact with each other and have a negative total Diopters. The optical lens of claim 1, wherein the first lens group comprises a first lens, a second lens and a third lens arranged in sequence from the magnification side toward the reduction side, the second lens group comprising a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged in this order from the magnification side toward the reduction side, wherein the fourth lens, the fifth lens, and the sixth lens are in contact with each other and have a negative total Diopting, the refractive index of the first lens falls within a range of 1.48 to 1.69, and the first lens, the second lens, the third lens, and the seventh lens are each provided with at least one aspherical surface, the fourth lens The fifth lens and the sixth lens are in contact with each other to form a three-glued lens, at least three lenses of the optical lens are formed of glass, and the fourth lens, the fifth lens and the sixth lens form a a triplet lens, and at least two of which have a negative refracting power, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh The diopter of the mirror is either: (1) negative, positive, positive, negative, positive, negative, and positive; or (2) negative, negative, positive, negative, positive, negative, and positive, the first The diopter of a lens group and the second lens group are both positive, and the optical lens satisfies the condition of 2.5 < TTL / EFL < 6.5, and EFL represents the effective focal length of the optical lens. An optical lens, sequentially arranged from an enlarged side to a reduced side, comprising: two lenses having a diopter; an aperture stop; and four lenses having a refracting power, wherein at least three of the four lenses are fixed to each other and have a negative The total diopter, TTL is the length measured along the optical axis between the opposite surfaces of the two lenses in the optical lens, and EFL is the effective focal length of the optical lens. The optical lens satisfies 2.5<TTL / EFL< Condition of 6.5. The optical lens according to claim 4, wherein the lens having the refracting power closest to the magnification side has an aspherical surface, and the lens having the refracting power closest to the reduced side has an aspherical surface and is formed of glass. The optical lens of claim 2 or 4, which satisfies the condition of TTL <100 mm and 2.5 <TTL / EFL <6.5, wherein TTL is the opposite surface of the two lenses farthest from the optical lens. Between the length measured along the optical axis, EFL is expressed as the effective focal length of the optical lens. The optical lens of claim 2, wherein the three lenses that are in contact with each other or fixed together are formed as a three-glued lens, and the three-glued lens includes at least two lenses having a negative refracting power. . The optical lens of claim 2, wherein the diopter of the three lenses is either: (1) negative, positive, positive; or (2) negative, negative, positive And the total diopter between the aperture stop and the enlarged side is positive, and the total diopter between the aperture stop and the reduced side is positive. The optical lens of claim 2 or 5, wherein the aperture diaphragm has three lenses between the aperture side and the magnification side, the three lenses all have diopter, and all three lenses have an aspherical surface. The optical lens according to claim 2, wherein the lens having the refracting power closest to the magnification side has a refractive index falling within a range of 1.48 to 1.69, and the optical lens has at least three lenses. Made of glass.